Author: jh
Date: Fri Jan 6 10:12:59 2012
New Revision: 229694
URL: http://svn.freebsd.org/changeset/base/229694
Log:
r222004 changed sbuf_finish() to not clear the buffer error status. As a
consequence sbuf_len() will return -1 for buffers which had the error
status set prior to sbuf_finish() call. This causes a problem in
pfs_read() which purposely uses a fixed size sbuf to discard bytes which
are not needed to fulfill the read request.
Work around the problem by using the full buffer length when
sbuf_finish() indicates an overflow. An overflowed sbuf with fixed size
is always full.
PR: kern/163076
Approved by: des
MFC after: 2 weeks
Modified:
head/sys/fs/pseudofs/pseudofs_vnops.c
Modified: head/sys/fs/pseudofs/pseudofs_vnops.c
==============================================================================
--- head/sys/fs/pseudofs/pseudofs_vnops.c Fri Jan 6 09:21:40 2012
(r229693)
+++ head/sys/fs/pseudofs/pseudofs_vnops.c Fri Jan 6 10:12:59 2012
(r229694)
@@ -630,14 +630,14 @@ pfs_read(struct vop_read_args *va)
if (uio->uio_offset < 0 || uio->uio_resid < 0 ||
(offset = uio->uio_offset) != uio->uio_offset ||
(resid = uio->uio_resid) != uio->uio_resid ||
- (buflen = offset + resid + 1) < offset || buflen > INT_MAX) {
+ (buflen = offset + resid) < offset || buflen >= INT_MAX) {
error = EINVAL;
goto ret;
}
- if (buflen > MAXPHYS + 1)
- buflen = MAXPHYS + 1;
+ if (buflen > MAXPHYS)
+ buflen = MAXPHYS;
- sb = sbuf_new(sb, NULL, buflen, 0);
+ sb = sbuf_new(sb, NULL, buflen + 1, 0);
if (sb == NULL) {
error = EIO;
goto ret;
@@ -650,8 +650,14 @@ pfs_read(struct vop_read_args *va)
goto ret;
}
- sbuf_finish(sb);
- error = uiomove_frombuf(sbuf_data(sb), sbuf_len(sb), uio);
+ /*
+ * XXX: If the buffer overflowed, sbuf_len() will not return
+ * the data length. Then just use the full length because an
+ * overflowed sbuf must be full.
+ */
+ if (sbuf_finish(sb) == 0)
+ buflen = sbuf_len(sb);
+ error = uiomove_frombuf(sbuf_data(sb), buflen, uio);
sbuf_delete(sb);
ret:
vn_lock(vn, locked | LK_RETRY);
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